Abstract
Fms-like tyrosine kinase-3 (FLT3) inhibitors have been used to overcome the dismal prognosis of acute myeloid leukemia (AML) with FLT3 mutations. Clinical results with FLT3 inhibitor monotherapy have shown that bone marrow responses are commonly less pronounced than peripheral blood responses. We investigated the role of p53 in bone marrow stromal cells in stromal cell-mediated resistance to FLT3 inhibition in FLT3 mutant AML. While the FLT3 inhibitor FI-700 induced apoptosis in FLT3 mutant AML cells, apoptosis induction was diminished under stromal coculture conditions. Protection appeared to be mediated, in part, by CXCL12 (SDF-1)/CXCR4 signaling. The protective effect of stromal cells was significantly reduced by pre-exposure to the HDM2 inhibitor Nutlin-3a. p53 activation by Nutlin-3a was not cytotoxic to stromal cells, but reduced CXCL12 mRNA levels and secretion of CXCL12 partially through p53-mediated HIF-1α down-regulation. Results show that p53 activation in stroma cells blunts stroma cell-mediated resistance to FLT3 inhibition, in part through down-regulation of CXCL12. This is the first report of Nutlin effect on the bone marrow environment. We suggest that combinations of HDM2 antagonists and FLT3 inhibitors may be effective in clinical trials targeting mutant FLT3 leukemias.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Adult
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Apoptosis / drug effects
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Bone Marrow Cells / drug effects
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Bone Marrow Cells / metabolism
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Chemokine CXCL12 / genetics*
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Down-Regulation / drug effects
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Gene Expression Regulation, Leukemic / drug effects
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Humans
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Hypoxia-Inducible Factor 1, alpha Subunit / genetics
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Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
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Imidazoles / pharmacology
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Leukemia, Myeloid, Acute / drug therapy*
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Leukemia, Myeloid, Acute / genetics
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Leukemia, Myeloid, Acute / metabolism
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Mesenchymal Stem Cells / drug effects*
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Mesenchymal Stem Cells / metabolism
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Mutation
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Piperazines / pharmacology
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Protein Kinase Inhibitors / pharmacology*
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Proto-Oncogene Proteins c-mdm2 / antagonists & inhibitors
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Proto-Oncogene Proteins c-mdm2 / metabolism
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Pyridines / pharmacology*
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Pyrimidines / pharmacology*
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Tumor Cells, Cultured
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Tumor Microenvironment / drug effects
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Tumor Suppressor Protein p53 / metabolism*
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Young Adult
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fms-Like Tyrosine Kinase 3 / antagonists & inhibitors*
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fms-Like Tyrosine Kinase 3 / genetics
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fms-Like Tyrosine Kinase 3 / metabolism
Substances
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Chemokine CXCL12
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FI-700
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Hypoxia-Inducible Factor 1, alpha Subunit
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Imidazoles
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Piperazines
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Protein Kinase Inhibitors
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Pyridines
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Pyrimidines
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Tumor Suppressor Protein p53
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nutlin 3
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MDM2 protein, human
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Proto-Oncogene Proteins c-mdm2
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fms-Like Tyrosine Kinase 3